1. Field of the Invention
Embodiments of the invention relate to methods of adjusting a processing stream to facilitate the sequential deposition of a film on a substrate.
2. Description of the Related Art
Atomic layer deposition (ALD) exposes a substrate to alternating reactants, and utilizes a phenomenon known as chemisorption to deposit alternating monolayers of reactive molecules on a substrate surface. For example, a first step of a conventional ALD process involves introducing a first reactive precursor into a processing chamber to chemisorb a first monolayer of molecules on a substrate surface. In a second step of a conventional ALD process, a non-reactive or purge gas is introduced into the processing chamber to remove the first reactive material from the chamber. In some cases, the purge step can last for about 2 to about 10 minutes. In a third step of a conventional ALD process, a second reactive precursor is introduced into the processing chamber to chemisorb a second monolayer of molecules adjacent the first monolayer. The adjacent monolayers react to form a desired film on the substrate surface. In a fifth step of a conventional ALD process, a purge gas is again introduced into the processing chamber to remove reactive material and reaction by-products from the chamber. In some cases, this purge step can also last for about 2 to about 10 minutes. The process steps described above are repeated until a desired film thickness is formed.
The desire to economically fabricate advanced semiconductor devices pushes processing sequences to ever increasing levels of performance and productivity. Slower rates of deposition due to multiple processing steps, such as those of a conventional ALD process are not helpful toward achieving competitive performance and productivity. Further, batch processes, which simultaneously process multiple wafers, are used to achieve a desired throughput of wafers per hour. As a result, any problem encountered during processing can result in the ruination of an entire batch of wafers. Additionally, the architecture of chambers for batch processing is complex and can cause variation in results from wafer to wafer within a batch.
There is a need, therefore, for a sequential deposition process having increased deposition rates. More particularly, there is a need for a deposition process that eliminates the need for substantially purging a processing chamber between the introduction of deposition gases.